Effects of thermal manipulation during embryogenesis and post‐hatch acute heat stress on the mRNA expression dynamics of cytokines in broiler chickens

Abstract

Heat stress significantly impacts chicken immunity and cytokine expression, but, the effects of embryonic thermal manipulation (TM) on cytokine expression in broiler chickens is unclear. The aim of the present study was to evaluate the effects of TM on the splenic mRNA expression dynamics of certain cytokines (IFN‐α, IFN‐β, IFN‐γ, IL‐4, IL‐8, IL‐15, IL‐16, IL‐17 and IL‐18) in broilers during subsequent exposure to acute heat stress (AHS). TM was performed by elevating the incubation temperature to 39°C at 65% relative humidity (RH) for 18 h daily during embryonic days (ED) 10 to 18. AHS was carried out by raising the temperature to 40°C for 7 h on post‐hatch day 28. At 0, 1, 3, 5, and 7 h of AHS, the spleen was collected from all groups to evaluate mRNA expression by relative‐quantitative real‐time RT‐PCR, and blood was collected to measure plasma levels of IL‐4, IL‐8, and IFN‐γ. At 0 h, TM led to a significant reduction in the basal mRNA level of IFN‐β and the plasma level of IFN‐γ and IL‐8. Moreover, AHS significantly decreased IFN‐β in control chicks, decreased IL‐4 in both TM and control chicks, and increased IFN‐γ and IL‐16 in TM chicks. IL‐8, IL‐15, IL‐17, IFN‐α, and IL‐18 expression significantly increased during AHS in both TM and control chicks, but expression dynamics was improved in TM chicks for all cytokines except IL‐17. AHS resulted in increased plasma IFN‐γ levels in TM chicks only, and it increased IL‐8 levels at 3 and 5 h of AHS in TM chicks but at 7 h in control chicks. Lastly, 3 h of AHS increased IL‐4 plasma levels in control chicks. The results of this study may indicate that TM has a long‐term effect on the expression dynamics of cytokines, especially during AHS, suggesting that TM affects post‐hatch immunity. Furthermore, this study may suggest that TM improves heat tolerance by increasing the expression of signaling proteins important to the wound‐healing process.Support or Funding InformationDeanship of Research/Jordan University of Science & Technology (Grant#: 128/2017).This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.